The present invention relates to a dynamo-electric machine which uses a permanent magnet for field system, and particularly to a method and a dynamo-electric machine for performing the drive and regeneration in a carrier system or transport system.
In a permanent magnet field type dynamo-electric machine of the prior art, an induced electromotive force E is determined by a constant magnetic flux Φ generated by a permanent magnet arranged in a rotor and a rotating angular speed ω of the dynamo-electric machine. That is, when the rotating angular speed ω (rotating speed) of the dynamo-electric machine is increased, the induced electromotive force is proportionally increased.
Accordingly, high torque can be obtained in a low-speed range, but operation in a high-speed range is difficult because the variable range of rotating speed is narrow. Therefore, it may be considered that the high-speed operation range is widened using a field weakening control technology.
Further, the mechanism which uses the centrifugal force by the spring and the governor is disclosed in the Japnese Patent application Laid-open No. 2000-155262 as a method of weakening the field by the magnetic flux generated by permanent magnets.
The method of widening the high speed operation range using the field weakening control technology described above has limitations of heat generation and efficiency decrease due to weakening field current.
Further, the structure of the spring and the governor becomes complex in the method disclosed in the Japanese Patent Application No. 2000-155262.